Two-faced? Rosetta's target comet may have a split personality

Is this comet a chimera? Rosetta's next target could be two bodies joined at the hip

The comet-chasing Rosetta spacecraft may have a surprise waiting when it narrows in on its target: It’s a twofer!

Comet 67P/Churyumov-Gerasimenko, sporting a hyphenated name, could also have a hyphenated body. Grainy images snapped by the European Space Agency spacecraft show that the comet seems to be made of two parts, a larger chunk and a smaller one.

“It’s not just a reasonably round potato,” said Rosetta project scientist Matt Taylor, describing the typical cometary profile. “It’s this very interesting shape.”

Keep in mind that the images are too small to be certain, Taylor said — Rosetta was around 12,000 kilometers away when it took that shot on July 14, so it still has a ways to go before it can confirm this oddball profile.

How Rosetta’s target came to be so strangely shaped remains a mystery. It’s possible that 67P/Churyumov-Gerasimenko is a contact binary, formed when two separate comets got smashed together early in the solar system's history. But it’s possible that the gravity from a massive object like Jupiter kneaded the comet into its duck-bodied form.

Whether or not it's a cometary chimera, the strange shape — which may not be all that uncommon — could help shed light on certain processes in the solar system.

"It gives you more of a story," Taylor said. "It complicates the picture — but it makes it a bit more of a fun picture as well."

Rosetta is now just 8,200 kilometers or so from the strange knobbly comet. After its rendezvous with the comet, it will escort 67P/Churyumov-Gerasimenko as it slingshots around the sun to study how the comet shrinks and changes after its close encounter with our home star.

The spacecraft will also deploy a lander that will touch down on the surface. That in itself will be a challenge, Taylor said, given that the gravity around the comet is similar to 100 millionths of what we experience here on Earth — and the team is going to have to make the landing stick.

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